• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.12
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• pp.1347-1355
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• 2009

This paper demonstrates the validity of spectral element analysis for modeling the high-frequency dynamic behaviors of a beam with a surface-bonded piezoelectric wafer through a laboratory test. In the spectral element analysis, the high-frequency electro-mechanical interaction can be considered properly with relatively low computational cost compared to the finite element analysis. In the verification test, a cantilever beam with a surface-bonded piezoelectric wafer is forced to be in steady-state motion by exerting the harmonic driving voltage signal on the piezoelectric wafer. A laser scanning vibrometer is used to obtain the overall dynamic responses of the structure such as resonance frequencies, the associated mode shapes, and frequency response functions up to 20 kHz. Then, these dynamic responses from the test are compared to those computed by the spectral element analysis. A two-dimensional finite analysis is conducted to obtain the asymptotic solutions for the comparison purpose as well.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.159-166
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• 2006

Chassis system has a large influence on ride quality, stability and NVH performance of a car. To improve the performance and reduce cost, the development of chassis modular assemblies is emphasized. To develop chassis corner modules, it is necessary to predict the performance of full vehicle motion such as ride, handling performance, NVH characteristics and durability of modules. In this paper, full vehicle test is performed to acquire the road load data of chassis corner module of passenger car. 3-axis simulator modeling are carried out to simulate reaction force analysis and fatigue analysis of new developed modules. Also, real simulator tests to validate performance of new developed modules are performed. We had developed the accelerated durability test procedure of KATECH PG and it is used to test chassis corner modules at laboratory and simulate durability performance. All these results have been provided to module and parts company and make an important role to develop chassis corner modules.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.37-43
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• 2005

A haptic steering system which reflects steering reaction torque has been developed for a fixed base vehicle simulator. The haptic steering system consists of a steering effort sensor, MR-clutch, AC servo motor and controller. In order to generate realistic steering torque feel to driver and at the same time to meet real-time simulation requirement, 3D torque map is constructed by experimental data and torque generation algorithm using the torque map has been also developed. 3D torque map is constructed using curve fitting and interpolation of the measured values of the steering angle, velocity and steering torque from actual slalom test on the proving ground. In order to carry out performance test of the developed haptic steering system, a fixed based vehicle simulator is constructed by integrating real time vehicle dynamics module, VR-video/audio module, and the haptic steering system. Steering torque and steering angle curves have been obtained from virtual testing in the vehicle simulator and performance of the haptic steering system has been evaluated.

• International Journal of Aeronautical and Space Sciences
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• v.4 no.1
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• pp.34-44
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• 2003

An advanced aeroelastic analysis using a computational structural dynamics (CSD), finite element method (FEM) and computational fluid dynamics (CFD) is presented in this Paper. A general aeroelastic analysis system is originally developed and applied to realistic design problems in the transonic flow region, where strong shock wave interactions exist. The present computational approach is based on the modal-based coupled nonlinear analysis with the matched-point concept and adopts the high-speed parallel processing technique on the low-cost network based PC-clustered machines. It can give very accurate and useful engineering data on the structural dynamic design of advanced flight vehicles. For the nonlinear unsteady aerodynamics in high transonic flow region, Euler equations using the unstructured grid system have been applied to easily consider complex configurations. It is typically shown that the advanced numerical approach can give very realistic and practical results for design engineers and safe flight tests. One can find that the present study conducts a virtual flutter flight test which are usually very dangerous in reality.

• ETRI Journal
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• v.32 no.1
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• pp.73-83
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• 2010

Combinatorial testing has been an active research area in recent years. One challenge in this area is dealing with the combinatorial explosion problem, which typically requires a very expensive computational process to find a good test set that covers all the combinations for a given interaction strength (t). Parallelization can be an effective approach to manage this computational cost, that is, by taking advantage of the recent advancement of multicore architectures. In line with such alluring prospects, this paper presents a new deterministic strategy, called multicore modified input parameter order (MC-MIPOG) based on an earlier strategy, input parameter order generalized (IPOG). Unlike its predecessor strategy, MC-MIPOG adopts a novel approach by removing control and data dependency to permit the harnessing of multicore systems. Experiments are undertaken to demonstrate speedup gain and to compare the proposed strategy with other strategies, including IPOG. The overall results demonstrate that MC-MIPOG outperforms most existing strategies (IPOG, IPOF, IPOF2, IPOG-D, ITCH, TConfig, Jenny, and TVG) in terms of test size within acceptable execution time. Unlike most strategies, MC-MIPOG is also capable of supporting high interaction strengths of t > 6.

• International journal of advanced smart convergence
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• v.5 no.4
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• pp.48-53
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• 2016

In this paper, all elements used in integrated infrastructure for job competency assessments of NCS (National Competency Standards) will be merged into assessment system using multiple devices(ASMD). NCS is a systematic approach on required abilities (knowledge, technical expertise, attitude) to process the tasks in the fields by industry. Competiveness of ASMD design is that no limitation of time and space using personal devices like PC, laptop, smartphone, and tablet, while seeing screen, hearing, touching, speaking, and writing. Question type can be limitless to express the situation. To lead technologies and market for domestic and oversea assessment system, supporting on multiple devices with connectivity that will eliminate limitation of time and space is the key feature for design competitiveness. Design of integrated assessment system proposed in this paper can be applied to NCS, fundamental competency evaluation, online test, job aptitude test, and foreign language test which involve listening, reading, writing, and speaking. Compared with existing evaluation method, reduction of investment and operating cost will be greater. Along with development of ICT technologies, the next generation of integrated assessment system will be quickly changed to ASMD, which already involves connected service between internet and smart devices.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.548-551
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• 2010

A 150 lbf-thrust class micro turbojet engine has been developed. The engine could be applied to power plant for small aviation vehicle such as UAV, decoy and anti-radar missile and was designed with concepts that has small size, low-cost and high performance. A prototype was manufactured and performed the ground static test and high altitude test. This paper outlines the features and layout of 150 lbf turbojet engine and also describes the design characteristics and test results of the engine and components.

• Ocean Systems Engineering
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• v.7 no.2
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• pp.107-120
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• 2017

Spud-can is used for fixing jack-up rig on seabed. It needs to be inserted up to the required depth during the installation process to secure enough soil reaction and prevent overturning accidents. On the other hand, it should be extracted from seabed soils as fast as possible during the extraction process to minimize the corresponding operational cost. To achieve such goals, spud-can may be equipped with water-jetting system including monitoring and control. To develop such a smart spud-can, a reliable numerical simulation tool is essential and it has also to be validated against physical model tests. In this regard, authors developed a numerical simulation tool by using a commercial program ANSYS with extended Drucker-Prager (EDP) formula. Authors also conducted small-scale (1/100) physical model tests for verification and calibration purpose. By using the numerical model, a systematic parametric study is conducted both for sand and K(kaolin)-clay with varying important soil parameters and the best estimated soil properties of the physical test are deduced. Then, by using the selected soil properties, the numerical and experimental results for a sand/K-clay multi-layer case are cross-checked to show reasonably good agreement. The validated numerical model will be useful in the next-stage study which includes controllable water-jetting.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.271-274
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• 2001

The purpose of interlocking system was to prevent the route for a train being set up and its protecting signal cleared if there was already another, conflicting route set up and the protecting signal for that route cleared. Recently, the computer based control systems instead of conventional relays circuitry are widely used to industrial systems, therefore, interlocking system are rapidly changing from relay interlocking system to Electronic Interlocking System(EIS) that control requirements of interlocking at junctions using electronic circuits. In this paper, by examine checking technique of EIS, we will to acquire interlocking inspection algorithm and method for EIS and to develope inspection system for EIS. By using inspection system we obtain every advantage. It has the functions for test data generation and automatic test execution, and it can operate on personal computer. Time and cost for test work can be reduced to more of those now required by using this developed inspection system.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.2
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• pp.70-76
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• 2004

The purpose of interlocking system in railway is to prevent the route for a train being set up and its protecting signal cleared if there were already another, conflicting route set up and the protecting signal for that route cleared. Recently, conventional relays circuitry in industrial field is replaced to computer-based control systems according to the advance of computer and communication technology. Therefore, interlocking systems in railway field are rapidly changing from existing relay-based interlocking system to computer-based electronic ones that executes the vital interlocking logic to assure the safety train routes at trackside signaling equipment room using electronic circuits. So it is very important to verify the performance of developed electronic interlocking system by plentiful laboratory testing before actually application in the railway system. However the laboratory testing in the present state of railway signaling is preformed individually by manual, so very much test time and cost are required. To solve these problems, we are developed the simulator for automatic interlocking inspection in this research. This simulator is able to operate on general personal computer and has following beneficial functions : automatic test sheet generation for inspection, automatic inspection execution and et al. The experiments are executed to test the feasibility of the developed simulator the experimental results have good agreements with the anticipated ones.